The effects of early stress can last a lifetime, affecting physical, mental, and social well-being across the lifespan. The effects of early stress may not be limited to the affected generation: trans-generational effects of early stress have been reported across species. This means that, at both the societal and individual level, the long-term health effects of early stress may be harder to alleviate than was previously understood. Identifying the mechanisms of the transgenerational effects of stress may help us understand why some stress-related traits and diseases run in families. The use of animal models to understand these transgenerational processes is critical because early life stress can be randomized and standardized in a laboratory setting. Additionally, rhesus macaques are ideal for examining the transgenerational effects of stress, as they are one of our most translatable animal models of human health and development. We have recently observed effects of fathers', but not mothers', experience of early maternal deprivation stress, or nursery rearing (NR), on infant rhesus macaque immunity and physiological stress response. Since fathers play little role in macaque postnatal development, this finding suggests that heritable factors may play a role. For many years, it would have been thought impossible that acquired changes to the genome could be passed on to offspring, because we did not know that genes could be changed in response to stress. We now know that epigenetic plasticity occurs in multiple tissues following early stress, and there is some evidence that these changes might be inherited. The proposed study will use a large sample of archived data to examine whether epigenetic factors play a role in the transgenerational health effects of NR stress in primates. Using archived samples collected from 3000 infant rhesus macaques during a standardized BioBehavioral Assessment Program available only at the California National Primate Research Center (CNPRC), we will first explore whether early NR stress epigenetically exacerbates inflammation and physiological stress response. Next, we will assess whether similar changes are observed in offspring and paternal grand-offspring of NR-exposed males. Finally, we will investigate whether NR-related epigenetic patterns are heritable via the paternal line. DNA methylation is one of the most stable epigenetic marks, so we will target promoter methylation patterns as a potential mechanism for the transgenerational effects of early stress in this study. The significance of this application is that we will use a highly translational animal model to explore how acquired stress-related health outcomes can be transmitted across generations, which may reveal new avenues for intervention to improve the health and quality of life of at-risk children and their families.